S40 V40: CEM Wiring/Repair Information

[Gladston]

Hi,
I am having a prblem opening the PDF's. I am a member but I am still struggling. Is it an issue or just my PC

Thanks

[amillar]

The attachment in Matt86's post here http://www.volvoforums.org.uk/showthread.php?t=67437 works fine for me - most of the others seem to have disappeared.

Many thanks to all on here for excellent postings - fixed O/S dipped headlight with £1.33's worth of relay from Farnell 910351 (although changed both N/S and O/S to be safe).

[Old Snail]

Originally Posted by Russell_S

Hi, I've recently had a headlight problem which, at first, appeared to be the common CEM issue (see this thread http://www.volvoforums.org.uk/showthread.php?t=67437) but finally turned out to be a break in the wiring loom. However, while fault finding the problem I found out a bit about the CEM which I thought others could find useful in faulfinding their own headlight related issues. I've taken a few pictures to help with this.

I have attached to this thread the Volvo wiring diagram for the CEM and headlights because the Haynes manual is worse than useless in this respect as it doesn't even show the CEM in their wiring diagrams.
I have also attached the data sheet for the Fujitsu relays that are used for the headlight switching in the CEM. I originally assumed that they would be solid state relays but in fact they are normal miniature PCB mounting mechanical relays so it they do fail then the data sheet could help find a replacement to repair the CEM.

Firstly, for those who don't know where the Central Electronics Module (CEM) is situated, here is a picture:



Next we have a picture of the CEM circuit board itself highlighting the headlight relays:



and now a picture of the CEM connectors and their pin numbering to go with the attached wiring diagram:



Hopefully others will find this information useful as the CEM does appear to be a weak component with respect to headlight switching.


Regards

Russell

Thank you for the information, I have just finished my repair and all is in working order. No issue in getting to the relay, (RHS) albeit I did find it somewhat difficult to remove the old one, ended up drilling out the pins. Had to break up old relay just to see what's inside, one small unit inside another! Anyway, thanks for your guidance, most helpfull.
Old Snail

[Cymro1986]

Anyone noticed that now the temperatures are dropping that CEM's are starting to play up again?

Mine played up the start of the year, has been fine all summer and now Drivers side light will sometimes go out.
Easy fix so far is a quick knock on the panel holding the CEM and on it comes again.

I have got a spare ready for when it goes from a V40 but dont think the other V40 had fog lights.

[druid]

You might be able to sent it to Gatos and he will reprogram it. Send him a PM!

[sco3ie]

Just like to say thanks to everyone for this thread. It keeps on giving! Replaced mine in my '02 S40, gaining kudos points from my mech friends. Got relays too late for my CEM, which I replaced with one from the breakers but I'll probably fix the original one and stick it on ebay to make some money back.

Well done, people

[shanegtr]

Big thanks to all who started this thread. I've just fixed my non working rear wiper (V40) and front intermittent wiper. Took me ages to finally order the relays, it was only when I re-read this thread I realised someone had posted the part on RS components. Good thing the australian site uses the same part number Anyway, I've updated the original photo with the relays I replaced

[Cymro1986]

Finally had enough of beating the living daylights out of my lower dashboard to get both my lights turn on and fitted my new CEM....what a difference.

Lights are now silly bright, drivers has been slowly becoming duller for the last month (the side with the dodgy relay), now both sides are same brightness and much brighter than before, plus I got lucky and the CEM I had was from a V40 with fogs so everything works.

[ma70]

Great thread & doubtless will be useful when I get mine home at last, since I have the left dipped beam out (amongst others lol).

Seeing as how I'm such a cheapskate though I think what I'll be doing after checking the bulb, is giving the dash a friendly "tap" above the bonnet release & see if that makes a difference, then if it does I'll dremel the lid off the relay & clean the contacts with a points file! (my reasoning being, if they take 10years+ for the arcing to build up crap from new, if I clean even 80% of it off I'll have good relays for 8years+ & that should be more than enough for my needs

I'll post back how I get on, if this is the course of action I take. Hoping it's just a bulb but I doubt it somehow... Just fed up of waiting now, next week till I can get the car home & time's dragging worse than lily savage!

[v40alex]

As a fellow cheapskate, sorry, I meant green environmentalist, I like the sound of relay repair. Do let us know how you get on.